The frailing banjo uses many different string tunings sometimes known as cross tunings. The ones I use most often are:
Open G tuning: gDGBD
Double C tuning: gCGCD
G Modal tuning: gDGCD
The lower case "g" refers to the 5th string (the one furthest from the floor when playing). Double C tuning is sometimes known as Drop C tuning. There are others which I use less frequently such as G minor tuning: gDGBflatD.
There are many more cross tunings. For a list of most of the other tunings, go to this page.
With this number of different tunings, it is easy to see why tablature is more practical for banjo than music notation. Using the latter would entail relearning the musical notes at every fret every time the banjo was re-tuned.
Cross tunings are also commonly used by guitarists when playing folk music. For example, when playing Celtic music, I often use D modal tuning: DADGAD (pronounced "dadgad") which makes the playing of Celtic modal harmonies much easier than the standard guitar tuning of EADGBE.
One of the most well known guitar cross-tuners is Joni Mitchell. For a list of guitar tunings she uses have a look at this page.
If you already play a fretted stringed instrument like the guitar or banjo, it is relatively easy to learn the mandolin as well. And the mandolin has the same tuning as a fiddle. There are cross tunings for mandolin which make learning mandolin tablature useful. However, it is also useful to learn musical notation for the mandolin because this means you can then read and play literally thousands of fiddle folk tunes from around the world in the many anthologies that exist. Once you know the melody of a tune from the fiddle notation, it is easy to knock out the tune, or an accompaniment, on the guitar or banjo as well. And once you are reasonably confident on the mandolin--this makes it is easier to learn the fiddle because you already know the left hand technique and notation.